MUMBAI: Ratan Tata, who led the transformation of the Tata group from a conventional corporate house into a $100 billion global conglomerate with high-profile acquisitions abroad, retires today ending a 50-year run in one of India's oldest business empires.

Marking a generational change, Tata, who turns 75 today, will hand over the reins of the group to 44-year-old Cyrus Mistry, who was chosen his successor last year and formally appointed Chairman earlier this month.

Lauding the retiring chairman of the group, JJ Irani, Former Director, Tata Sons said, "What Ratan Tata has left behind is that he has taught the group to think big. When he took over, I do not think our combined turnover was even $10 billion. In the last 20 years, it has increased to $100 billion."

"The opportunity was there. He grabbed it and he taught all the companies to think big and most importantly to think beyond the shores of India," he told ET Now.

Echoing a similar sentiment AM Naik, Executive Chairman, L&T said that Ratan Tata has taken the group to 'different heights altogether'. "The sales have gone up almost 43 times during his tenure. The profit has gone up over 50 times. He has 28 odd listed entities all doing well and the Tata Group's logo has improved its value considerably. Tata was always a good brand but he has taken it to be the No. 1 brand of India," Naik said.

Rahul Bajaj, Chairman of Bajaj Auto feels that Ratan Tata has maintained the 'Tata DNA'. "This is especially with respect to value systems and ethical values. He has fully maintained that. As he says maybe in terms of growth and the rate of growth, the group had to sometimes pay a price, but because of him, the Tata Group did not compromise on values and on ethical business dealing. So he has done a great job," he said.

Harsh Goenka, Chairman of RPG Enterprises believes that the single largest success of the Tata Group is a small company Titan. "The reason behind it is, India has been very poor in terms of design. We do not have any world class products which we can be proud of. Titan has been one product which has world class designs as far as watches are concerned and it is now diversified into jewellery and now into many more things," Goenka told ET Now.

Tata is hanging up his boots after steering the group for 21 years as its Chairman, when he succeeded the legendary JRD Tata. While JRD made Tata the Chairman out of the blue in 1991, Mistry of the Shapoorji Pallonji group and whose family owns 18 per cent stake in Tata Sons, was chosen by a five-member selection committee.